Inside the QANTAS flight simulator 1:56

AIRLINE pilots are banned from small talk during take off and landing because of a little known rule introduced after a horror crash that claimed 72 lives.

The strictly enforced Sterile Cockpit Rule means pilots are barely allowed to talk to each other if their aircraft is flying below 10,000 feet (about three kilometres).

The law instructs pilots to focus entirely on “their essential operational activities” and “avoid non-essential conversations”, The Sun reports.

It also bans crew members or pilots from “eating meals and holding non-essential communications with cabin crews”.

It states this rule applies below 10,000 feet, and during taxi, takeoff and landing.

The regulation was introduced in 1974 in response to the crash of Eastern Air Lines flight 212. The plane infamously fell just short of the runway at North Carolina’s Charlotte Douglas International airport in heavy fog, with the loss of 72 lives.

Despite the poor visibility, investigators determined the cause of the crash was, in part, due to “the flight crew’s lack of altitude awareness at critical points during the approach”.

They put this down to “poor cockpit discipline”.

The US National Transportation Safety Board (NTSB) found during the approach the crew were engaged in conversations ranging from “politics to used cars”.

It ruled this would have been distracting enough for the pilots to fail to check their instruments properly.

“Sterile flight deck procedures are meant to increase the flight crew members’ attention to their essential operational activities when their focused alert is needed,” reads the code, which applies to all aviation authorities.

The US Federal Aviation Administration introduced the Sterile Cockpit Rule seven years after the Charlotte crash, amid fears flights decks had become too cosy and relaxed.

The rule means pilots can’t chitchat in the cockpit during critical times of the flight, including takeoff and landing.Source:ThinkStock

The rule, which all airlines are required to enforce, forbids “any duties during a critical phase of flight except those duties required for the safe operation of the aircraft”, citing as example, calls for galley supplies, confirming passenger connections, or airline promotions over the tannoy.

BUT WHAT IF THERE’S AN EMERGENCY IN THE CABIN?

There has been reported confusion as to when exactly flight attendants should break their silence because of the Sterile Cockpit Rule.

The FAA noted: “Hesitancy or reluctance on the part of a flight attendant to contact the flight crew members with important safety information because of a misconception of the sterile cockpit rule is potentially even more serious than the unnecessary distraction caused by needless violations of the sterile cockpit.”

In 1995, a flight attendant watched a passenger door seal separate just after takeoff but did not contact the pilot because of the rule of silence.

Japan Airlines, in order to avoid any confusion, listed the instances when it believes flight attendants should contact the cockpit below 10,000 feet.

They include any outbreak of fire, the presence of smoke in the cabin, any abnormality in the attitude of the aircraft during takeoff and landing, the existence of any abnormal noise or vibration, and the observance of any fuel or other leakages.

This article originally appeared on The Sun and was reproduced with permission.